Garry Hallam Posted May 4, 2007 Share Posted May 4, 2007 Hi, This looks like a great electric trainer and a good size to learn with as opposed to the usually smaller Electrics. I would like to build it, however, The Brushless setup is a little expensive for me right now!Is there a brushed motor that could be used instead?garry Quote Link to comment Share on other sites More sharing options...
Garry Hallam Posted May 10, 2007 Author Share Posted May 10, 2007 Well No replys! having done some research I am going to try a 600 Motor with a 2.5:1 Gearbox and the 11x7 folding Prop.I may use lipo's to reduce the added weight of the Motor & Gearbox. Quote Link to comment Share on other sites More sharing options...
Tony Patman Posted May 10, 2007 Share Posted May 10, 2007 Here's a reply, Garry! I want to build this too, as it looks like a good model to introduce me to leccy flight, but I left the magazine on the bl**dy train... Quote Link to comment Share on other sites More sharing options...
Garry Hallam Posted May 10, 2007 Author Share Posted May 10, 2007 Back to the Newsagents for you then I guess?Watch out for that guy on the train carrying a pogostick :) Quote Link to comment Share on other sites More sharing options...
Alistair Taylor Posted May 10, 2007 Share Posted May 10, 2007 GarryA geared speed 600 would be a good way to go, but you might even want to go to a longer ratio (3.33:1) and even larger prop - 12 x 8 or 12 x 10.This was the same setup as recommended for the 45" Nigel Hawes tucano, running on 8 NiCAD/NiMH cells.Although with the prices of APC-E props you may end up spending as much on props as a cheap brushless setup would cost.AlistairT Quote Link to comment Share on other sites More sharing options...
Garry Hallam Posted May 10, 2007 Author Share Posted May 10, 2007 AlistairThanks for that. In fact the Gearbox is one I will be making myself as I have done previously and has interchangable Pinnions for different ratios.Will have to check out the Prices on those Props.Garry Quote Link to comment Share on other sites More sharing options...
Garry Hallam Posted May 17, 2007 Author Share Posted May 17, 2007 Well I got the Gearbox Made with a ratio of 2.43:1 to begin with. The Graupner speed 600 8.4v 21000 rpm race motor arrived today and should give 8641rpm at the prop and I will try a 12x7 Folding Prop.Problem is that the Motor needs reversing as it is a simple 2 Gear gearbox. I was just going to reverse the polarity of the Motor as I have done in the Past, but I came across an article on the web that described making Physical modifications to do the Job (Basically involves moving the Motor Back Plate around by about 10 degrees)Anybody know what the Pro's and cons of doing it either way?Any help appreciatedGarry Quote Link to comment Share on other sites More sharing options...
Alistair Taylor Posted May 17, 2007 Share Posted May 17, 2007 GarryYou will have to reverse the electrical connections to get reverse rotation, whatever you do. The web-article refers to re-timing the motor by rotating the backplate, which can improve the efficiency of the motor, and gain you a few rpms at the prop.Basically the brushes on the motor are "advanced" by a few degrees, a bit like the ignition on spark-ignition engines, usually to give the best compromise of RPMs and efficiency.Changing this degree of advance can give you more RPMs (at the expense of efficiency), or more efficiency (at the expense of RPMs). Running the motor in reverse effectively means that the brushes are several degrees away from the optimum position - so in the ideal world you would rotate them to this position.For your motor, you will probably have to grind away the tabs holding the backplate in, and then rotate it by hand, or with appropriately shaped pliers.For more info on what to do see;http://www.rcgroups.com/forums/showthread.php?t=97414This thread refers to a speed 370 motor, but the principle is the same. It suggestst that, "Overall you gain aprox 10% to 14% more rpm for the same amount of current draw"Which is not to be sniffed at!AlistairT Quote Link to comment Share on other sites More sharing options...
Alistair Taylor Posted May 17, 2007 Share Posted May 17, 2007 GaryYou're in luck.Someone's done this before;http://www.ef-uk.net/data/speed600race.htmLooks like it's not as much of a trauma as I first thought.Alistair Quote Link to comment Share on other sites More sharing options...
Garry Hallam Posted May 17, 2007 Author Share Posted May 17, 2007 AlastairThat was the very article I was refering to! Everything is clear now, I thought the modification actually reversed the rotation without needing to reverse the Polarity. Even at the lower end of the expected increase in RPM will bring it up to 9500 RPM which would seen Ideal. Just wish I had a RPM counter to check Before and after!Hell,I may even Put Ball race bearings in, as he describes while I'm doing it!Thanks for your HelpRegardsGarry Quote Link to comment Share on other sites More sharing options...
Garry Hallam Posted May 23, 2007 Author Share Posted May 23, 2007 Has anybody else built this Model. I am at the Stage of completing the Wings and the Plan shows 3 Braces, yet the Magazine article refers to 5 of them?Anybody? Quote Link to comment Share on other sites More sharing options...
Garry Hallam Posted May 23, 2007 Author Share Posted May 23, 2007 I figured it out now regarding the 5 Braces! They are top & Bottom of the Spars + the Leading Edge. A side Section on the Drawing would be nice.garry Quote Link to comment Share on other sites More sharing options...
David Ashby - Moderator Posted May 23, 2007 Share Posted May 23, 2007 Have you seen the extra pics in the gallery Garry? Quote Link to comment Share on other sites More sharing options...
Garry Hallam Posted May 23, 2007 Author Share Posted May 23, 2007 No, I hadn't seen them David, but I'll make my way there now - Thanks for that!garry Quote Link to comment Share on other sites More sharing options...
Garry Hallam Posted June 6, 2007 Author Share Posted June 6, 2007 Well I finally finished off the Pogostick, I am just awaiting delivery of the Battery & Speed controller now. Here are some Pictures of her. Quote Link to comment Share on other sites More sharing options...
Alistair Taylor Posted June 6, 2007 Share Posted June 6, 2007 Very nice!The transparent film really shows off the structure well.Bonne chance with the maiden flights.AlistairT Quote Link to comment Share on other sites More sharing options...
Garry Hallam Posted June 6, 2007 Author Share Posted June 6, 2007 RE: The maiden Flights, I need to check for any twisting in the Wings and ailerons yet and adjust as neccasary. I do know that the ailerons are definately slightly twisted owing to their very light construction.Incidentally it comes in at 1400gram weight, as chris's did, despite the addition of the gearbox. I have ordered the same 3300mah battery, just hope it fits now!garry Quote Link to comment Share on other sites More sharing options...
David Ashby - Moderator Posted June 7, 2007 Share Posted June 7, 2007 Nice one Garry! Quote Link to comment Share on other sites More sharing options...
Garry Hallam Posted June 14, 2007 Author Share Posted June 14, 2007 Well, My 8.4v 3300mah Battery & Castle Creations Phoenix 35p Speed controller arrived yesterday so I set them up as well as altering the Timing on the Motor. Everything seems great swinging the 12x7 Folding Prop and I was surprised at the low current draw at only 12.8 Amps full throttle, Just need to tidy a few things up now and will be ready for the Maiden Flight.I am however concerned that when the Prop folds back it can get locked in place by the Wind Band dowels. No Problem at take off as they can be pushed out before starting...however, if it does this during a flight at throtle down then there will be a definate problem! Anybody have any Idea's on overcoming this?Garry Quote Link to comment Share on other sites More sharing options...
Alistair Taylor Posted June 14, 2007 Share Posted June 14, 2007 Once you've put the wing bands on, place a short length of tape from the fus to the top of the dowel and down again, to act as a sort of "fender" to prevent the prop getting stuck underneath.Otherwise just fit a fixed prop - you may find that prop braking (which you don't get so much with a folder) is helpful for slowing down for landing.AlistairT Quote Link to comment Share on other sites More sharing options...
Garry Hallam Posted June 14, 2007 Author Share Posted June 14, 2007 Thanks for the Suggestion Alistair, However I thought of a more permanent solution by making a thin Brass plate stopper which sits behind the Hub with a hole that goes over the shaft. It is kept in place radially by the Spinner. In the event of a bad landing it bends back again to its originl position. the extra weight is only 3.8 gram - which is nothing to speak of really.I have included a photo to show it more clearly.Garry Quote Link to comment Share on other sites More sharing options...
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